/* Copyright (c) 2001 Matej Pfajfar.
 * Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
 * \file nodelist.c
 *
 * \brief Structures and functions for tracking what we know about the routers
 *   on the Tor network, and correlating information from networkstatus,
 *   routerinfo, and microdescs.
 *
 * The key structure here is node_t: that's the canonical way to refer
 * to a Tor relay that we might want to build a circuit through.  Every
 * node_t has either a routerinfo_t, or a routerstatus_t from the current
 * networkstatus consensus.  If it has a routerstatus_t, it will also
 * need to have a microdesc_t before you can use it for circuits.
 *
 * The nodelist_t is a global singleton that maps identities to node_t
 * objects.  Access them with the node_get_*() functions.  The nodelist_t
 * is maintained by calls throughout the codebase
 *
 * Generally, other code should not have to reach inside a node_t to
 * see what information it has.  Instead, you should call one of the
 * many accessor functions that works on a generic node_t.  If there
 * isn't one that does what you need, it's better to make such a function,
 * and then use it.
 *
 * For historical reasons, some of the functions that select a node_t
 * from the list of all usable node_t objects are in the routerlist.c
 * module, since they originally selected a routerinfo_t. (TODO: They
 * should move!)
 *
 * (TODO: Perhaps someday we should abstract the remaining ways of
 * talking about a relay to also be node_t instances. Those would be
 * routerstatus_t as used for directory requests, and dir_server_t as
 * used for authorities and fallback directories.)
 */

#define NODELIST_PRIVATE

#include "core/or/or.h"
#include "app/config/config.h"
#include "core/mainloop/mainloop.h"
#include "core/mainloop/netstatus.h"
#include "core/or/address_set.h"
#include "core/or/policies.h"
#include "core/or/protover.h"
#include "feature/client/bridges.h"
#include "feature/client/entrynodes.h"
#include "feature/control/control_events.h"
#include "feature/dirauth/process_descs.h"
#include "feature/dirclient/dirclient_modes.h"
#include "feature/hs/hs_client.h"
#include "feature/hs/hs_common.h"
#include "feature/nodelist/describe.h"
#include "feature/nodelist/dirlist.h"
#include "feature/nodelist/microdesc.h"
#include "feature/nodelist/networkstatus.h"
#include "feature/nodelist/node_select.h"
#include "feature/nodelist/nodefamily.h"
#include "feature/nodelist/nodelist.h"
#include "feature/nodelist/routerlist.h"
#include "feature/nodelist/routerset.h"
#include "feature/nodelist/torcert.h"
#include "feature/rend/rendservice.h"
#include "lib/encoding/binascii.h"
#include "lib/err/backtrace.h"
#include "lib/geoip/geoip.h"
#include "lib/net/address.h"

#include <string.h>

#include "feature/dirauth/authmode.h"

#include "feature/dirclient/dir_server_st.h"
#include "feature/nodelist/microdesc_st.h"
#include "feature/nodelist/networkstatus_st.h"
#include "feature/nodelist/node_st.h"
#include "feature/nodelist/routerinfo_st.h"
#include "feature/nodelist/routerlist_st.h"
#include "feature/nodelist/routerstatus_st.h"

static void nodelist_drop_node(node_t *node, int remove_from_ht);
#define node_free(val) \
  FREE_AND_NULL(node_t, node_free_, (val))
static void node_free_(node_t *node);

/** count_usable_descriptors counts descriptors with these flag(s)
 */
typedef enum {
  /* All descriptors regardless of flags or exit policies */
  USABLE_DESCRIPTOR_ALL         = 0U,
  /* Only count descriptors with an exit policy that allows at least one port
   */
  USABLE_DESCRIPTOR_EXIT_POLICY = 1U << 0,
  /* Only count descriptors for relays that have the exit flag in the
   * consensus */
  USABLE_DESCRIPTOR_EXIT_FLAG   = 1U << 1,
  /* Only count descriptors for relays that have the policy and the flag */
  USABLE_DESCRIPTOR_EXIT_POLICY_AND_FLAG = (USABLE_DESCRIPTOR_EXIT_POLICY |
                                            USABLE_DESCRIPTOR_EXIT_FLAG)
} usable_descriptor_t;
static void count_usable_descriptors(int *num_present,
                                     int *num_usable,
                                     smartlist_t *descs_out,
                                     const networkstatus_t *consensus,
                                     time_t now,
                                     routerset_t *in_set,
                                     usable_descriptor_t exit_only);
static void update_router_have_minimum_dir_info(void);
static double get_frac_paths_needed_for_circs(const or_options_t *options,
                                              const networkstatus_t *ns);
static void node_add_to_address_set(const node_t *node);

/** A nodelist_t holds a node_t object for every router we're "willing to use
 * for something".  Specifically, it should hold a node_t for every node that
 * is currently in the routerlist, or currently in the consensus we're using.
 */
typedef struct nodelist_t {
  /* A list of all the nodes. */
  smartlist_t *nodes;
  /* Hash table to map from node ID digest to node. */
  HT_HEAD(nodelist_map, node_t) nodes_by_id;
  /* Hash table to map from node Ed25519 ID to node.
   *
   * Whenever a node's routerinfo or microdescriptor is about to change,
   * you should remove it from this map with node_remove_from_ed25519_map().
   * Whenever a node's routerinfo or microdescriptor has just changed,
   * you should add it to this map with node_add_to_ed25519_map().
   */
  HT_HEAD(nodelist_ed_map, node_t) nodes_by_ed_id;

  /* Set of addresses that belong to nodes we believe in. */
  address_set_t *node_addrs;

  /* Set of addresses + port that belong to nodes we know and that we don't
   * allow network re-entry towards them. */
  digestmap_t *reentry_set;

  /* The valid-after time of the last live consensus that initialized the
   * nodelist.  We use this to detect outdated nodelists that need to be
   * rebuilt using a newer consensus. */
  time_t live_consensus_valid_after;
} nodelist_t;

static inline unsigned int
node_id_hash(const node_t *node)
{
  return (unsigned) siphash24g(node->identity, DIGEST_LEN);
}

static inline unsigned int
node_id_eq(const node_t *node1, const node_t *node2)
{
  return tor_memeq(node1->identity, node2->identity, DIGEST_LEN);
}

HT_PROTOTYPE(nodelist_map, node_t, ht_ent, node_id_hash, node_id_eq);
HT_GENERATE2(nodelist_map, node_t, ht_ent, node_id_hash, node_id_eq,
             0.6, tor_reallocarray_, tor_free_);

static inline unsigned int
node_ed_id_hash(const node_t *node)
{
  return (unsigned) siphash24g(node->ed25519_id.pubkey, ED25519_PUBKEY_LEN);
}

static inline unsigned int
node_ed_id_eq(const node_t *node1, const node_t *node2)
{
  return ed25519_pubkey_eq(&node1->ed25519_id, &node2->ed25519_id);
}

HT_PROTOTYPE(nodelist_ed_map, node_t, ed_ht_ent, node_ed_id_hash,
             node_ed_id_eq);
HT_GENERATE2(nodelist_ed_map, node_t, ed_ht_ent, node_ed_id_hash,
             node_ed_id_eq, 0.6, tor_reallocarray_, tor_free_);

/** The global nodelist. */
static nodelist_t *the_nodelist=NULL;

/** Create an empty nodelist if we haven't done so already. */
static void
init_nodelist(void)
{
  if (PREDICT_UNLIKELY(the_nodelist == NULL)) {
    the_nodelist = tor_malloc_zero(sizeof(nodelist_t));
    HT_INIT(nodelist_map, &the_nodelist->nodes_by_id);
    HT_INIT(nodelist_ed_map, &the_nodelist->nodes_by_ed_id);
    the_nodelist->nodes = smartlist_new();
  }
}

/** As node_get_by_id, but returns a non-const pointer */
MOCK_IMPL(node_t *,
node_get_mutable_by_id,(const char *identity_digest))
{
  node_t search, *node;
  if (PREDICT_UNLIKELY(the_nodelist == NULL))
    return NULL;

  memcpy(&search.identity, identity_digest, DIGEST_LEN);
  node = HT_FIND(nodelist_map, &the_nodelist->nodes_by_id, &search);
  return node;
}

/** As node_get_by_ed25519_id, but returns a non-const pointer */
node_t *
node_get_mutable_by_ed25519_id(const ed25519_public_key_t *ed_id)
{
  node_t search, *node;
  if (PREDICT_UNLIKELY(the_nodelist == NULL))
    return NULL;
  if (BUG(ed_id == NULL) || BUG(ed25519_public_key_is_zero(ed_id)))
    return NULL;

  memcpy(&search.ed25519_id, ed_id, sizeof(search.ed25519_id));
  node = HT_FIND(nodelist_ed_map, &the_nodelist->nodes_by_ed_id, &search);
  return node;
}

/** Return the node_t whose identity is <b>identity_digest</b>, or NULL
 * if no such node exists. */
MOCK_IMPL(const node_t *,
node_get_by_id,(const char *identity_digest))
{
  return node_get_mutable_by_id(identity_digest);
}

/** Return the node_t whose ed25519 identity is <b>ed_id</b>, or NULL
 * if no such node exists. */
MOCK_IMPL(const node_t *,
node_get_by_ed25519_id,(const ed25519_public_key_t *ed_id))
{
  return node_get_mutable_by_ed25519_id(ed_id);
}

/** Internal: return the node_t whose identity_digest is
 * <b>identity_digest</b>.  If none exists, create a new one, add it to the
 * nodelist, and return it.
 *
 * Requires that the nodelist be initialized.
 */
static node_t *
node_get_or_create(const char *identity_digest)
{
  node_t *node;

  if ((node = node_get_mutable_by_id(identity_digest)))
    return node;

  node = tor_malloc_zero(sizeof(node_t));
  memcpy(node->identity, identity_digest, DIGEST_LEN);
  HT_INSERT(nodelist_map, &the_nodelist->nodes_by_id, node);

  smartlist_add(the_nodelist->nodes, node);
  node->nodelist_idx = smartlist_len(the_nodelist->nodes) - 1;

  node->country = -1;

  return node;
}

/** Remove <b>node</b> from the ed25519 map (if it present), and
 * set its ed25519_id field to zero. */
static int
node_remove_from_ed25519_map(node_t *node)
{
  tor_assert(the_nodelist);
  tor_assert(node);

  if (ed25519_public_key_is_zero(&node->ed25519_id)) {
    return 0;
  }

  int rv = 0;
  node_t *search =
    HT_FIND(nodelist_ed_map, &the_nodelist->nodes_by_ed_id, node);
  if (BUG(search != node)) {
    goto clear_and_return;
  }

  search = HT_REMOVE(nodelist_ed_map, &the_nodelist->nodes_by_ed_id, node);
  tor_assert(search == node);
  rv = 1;

 clear_and_return:
  memset(&node->ed25519_id, 0, sizeof(node->ed25519_id));
  return rv;
}

/** Helper function to log details of duplicated ed2559_ids */
static void
node_log_dup_ed_id(const node_t *old, const node_t *node, const char *ed_id)
{
  char *s;
  char *olddesc = tor_strdup(node_describe(old));

  tor_asprintf(&s, "Reused ed25519_id %s: old %s new %s", ed_id,
               olddesc, node_describe(node));
  log_backtrace(LOG_NOTICE, LD_DIR, s);
  tor_free(olddesc);
  tor_free(s);
}

/** If <b>node</b> has an ed25519 id, and it is not already in the ed25519 id
 * map, set its ed25519_id field, and add it to the ed25519 map.
 */
static int
node_add_to_ed25519_map(node_t *node)
{
  tor_assert(the_nodelist);
  tor_assert(node);

  if (! ed25519_public_key_is_zero(&node->ed25519_id)) {
    return 0;
  }

  const ed25519_public_key_t *key = node_get_ed25519_id(node);
  if (!key) {
    return 0;
  }

  node_t *old;
  memcpy(&node->ed25519_id, key, sizeof(node->ed25519_id));
  old = HT_FIND(nodelist_ed_map, &the_nodelist->nodes_by_ed_id, node);
  if (old) {
    char ed_id[BASE32_BUFSIZE(sizeof(key->pubkey))];

    base32_encode(ed_id, sizeof(ed_id), (const char *)key->pubkey,
                  sizeof(key->pubkey));
    if (BUG(old == node)) {
      /* Actual bug: all callers of this function call
       * node_remove_from_ed25519_map first. */
      log_err(LD_BUG,
              "Unexpectedly found deleted node with ed25519_id %s", ed_id);
    } else {
      /* Distinct nodes sharing a ed25519 id, possibly due to relay
       * misconfiguration.  The key pinning might not catch this,
       * possibly due to downloading a missing descriptor during
       * consensus voting. */
      node_log_dup_ed_id(old, node, ed_id);
      memset(&node->ed25519_id, 0, sizeof(node->ed25519_id));
    }
    return 0;
  }

  HT_INSERT(nodelist_ed_map, &the_nodelist->nodes_by_ed_id, node);
  return 1;
}

/* For a given <b>node</b> for the consensus <b>ns</b>, set the hsdir index
 * for the node, both current and next if possible. This can only fails if the
 * node_t ed25519 identity key can't be found which would be a bug. */
STATIC void
node_set_hsdir_index(node_t *node, const networkstatus_t *ns)
{
  time_t now = approx_time();
  const ed25519_public_key_t *node_identity_pk;
  uint8_t *fetch_srv = NULL, *store_first_srv = NULL, *store_second_srv = NULL;
  uint64_t next_time_period_num, current_time_period_num;
  uint64_t fetch_tp, store_first_tp, store_second_tp;

  tor_assert(node);
  tor_assert(ns);

  if (!networkstatus_consensus_reasonably_live(ns, now)) {
    static struct ratelim_t live_consensus_ratelim = RATELIM_INIT(30 * 60);
    log_fn_ratelim(&live_consensus_ratelim, LOG_INFO, LD_GENERAL,
                   "Not setting hsdir index with a non-live consensus.");
    goto done;
  }

  node_identity_pk = node_get_ed25519_id(node);
  if (node_identity_pk == NULL) {
    log_debug(LD_GENERAL, "ed25519 identity public key not found when "
                          "trying to build the hsdir indexes for node %s",
              node_describe(node));
    goto done;
  }

  /* Get the current and next time period number. */
  current_time_period_num = hs_get_time_period_num(0);
  next_time_period_num = hs_get_next_time_period_num(0);

  /* We always use the current time period for fetching descs */
  fetch_tp = current_time_period_num;

  /* Now extract the needed SRVs and time periods for building hsdir indices */
  if (hs_in_period_between_tp_and_srv(ns, now)) {
    fetch_srv = hs_get_current_srv(fetch_tp, ns);

    store_first_tp = hs_get_previous_time_period_num(0);
    store_second_tp = current_time_period_num;
  } else {
    fetch_srv = hs_get_previous_srv(fetch_tp, ns);

    store_first_tp = current_time_period_num;
    store_second_tp = next_time_period_num;
  }

  /* We always use the old SRV for storing the first descriptor and the latest
   * SRV for storing the second descriptor */
  store_first_srv = hs_get_previous_srv(store_first_tp, ns);
  store_second_srv = hs_get_current_srv(store_second_tp, ns);

  /* Build the fetch index. */
  hs_build_hsdir_index(node_identity_pk, fetch_srv, fetch_tp,
                       node->hsdir_index.fetch);

  /* If we are in the time segment between SRV#N and TP#N, the fetch index is
     the same as the first store index */
  if (!hs_in_period_between_tp_and_srv(ns, now)) {
    memcpy(node->hsdir_index.store_first, node->hsdir_index.fetch,
           sizeof(node->hsdir_index.store_first));
  } else {
    hs_build_hsdir_index(node_identity_pk, store_first_srv, store_first_tp,
                         node->hsdir_index.store_first);
  }

  /* If we are in the time segment between TP#N and SRV#N+1, the fetch index is
     the same as the second store index */
  if (hs_in_period_between_tp_and_srv(ns, now)) {
    memcpy(node->hsdir_index.store_second, node->hsdir_index.fetch,
           sizeof(node->hsdir_index.store_second));
  } else {
    hs_build_hsdir_index(node_identity_pk, store_second_srv, store_second_tp,
                         node->hsdir_index.store_second);
  }

 done:
  tor_free(fetch_srv);
  tor_free(store_first_srv);
  tor_free(store_second_srv);
  return;
}

/** Called when a node's address changes. */
static void
node_addrs_changed(node_t *node)
{
  node->last_reachable = node->last_reachable6 = 0;
  node->country = -1;
}

/** Add all address information about <b>node</b> to the current address
 * set (if there is one).
 */
static void
node_add_to_address_set(const node_t *node)
{
  if (!the_nodelist ||
      !the_nodelist->node_addrs || !the_nodelist->reentry_set)
    return;

  /* These various address sources can be redundant, but it's likely faster to
   * add them all than to compare them all for equality.
   *
   * For relays, we only add the ORPort in the addr+port set since we want to
   * allow re-entry into the network to the DirPort so the self reachability
   * test succeeds and thus the 0 value for the DirPort. */

  if (node->rs) {
    if (!tor_addr_is_null(&node->rs->ipv4_addr))
      nodelist_add_addr_to_address_set(&node->rs->ipv4_addr,
                                       node->rs->ipv4_orport, 0);
    if (!tor_addr_is_null(&node->rs->ipv6_addr))
      nodelist_add_addr_to_address_set(&node->rs->ipv6_addr,
                                       node->rs->ipv6_orport, 0);
  }
  if (node->ri) {
    if (!tor_addr_is_null(&node->ri->ipv4_addr))
      nodelist_add_addr_to_address_set(&node->ri->ipv4_addr,
                                       node->ri->ipv4_orport, 0);
    if (!tor_addr_is_null(&node->ri->ipv6_addr))
      nodelist_add_addr_to_address_set(&node->ri->ipv6_addr,
                                       node->ri->ipv6_orport, 0);
  }
  if (node->md) {
    if (!tor_addr_is_null(&node->md->ipv6_addr))
      nodelist_add_addr_to_address_set(&node->md->ipv6_addr,
                                       node->md->ipv6_orport, 0);
  }
}

/** Build a construction for the reentry set consisting of an address and port
 * pair.
 *
 * If the given address is _not_ AF_INET or AF_INET6, then the item is an
 * array of 0s.
 *
 * Return a pointer to a static buffer containing the item. Next call to this
 * function invalidates its previous content. */
static char *
build_addr_port_item(const tor_addr_t *addr, const uint16_t port)
{
  /* At most 16 bytes are put in this (IPv6) and then 2 bytes for the port
   * which is within the maximum of 20 bytes (DIGEST_LEN). */
  static char data[DIGEST_LEN];

  memset(data, 0, sizeof(data));
  switch (tor_addr_family(addr)) {
  case AF_INET:
    memcpy(data, &addr->addr.in_addr.s_addr, 4);
    break;
  case AF_INET6:
    memcpy(data, &addr->addr.in6_addr.s6_addr, 16);
    break;
  case AF_UNSPEC:
    /* Leave the 0. */
    break;
  default:
    /* LCOV_EXCL_START */
    tor_fragile_assert();
    /* LCOV_EXCL_STOP */
  }

  memcpy(data + 16, &port, sizeof(port));
  return data;
}

/** Add the given address into the nodelist address set. */
void
nodelist_add_addr_to_address_set(const tor_addr_t *addr,
                                 uint16_t or_port, uint16_t dir_port)
{
  if (BUG(!addr) || tor_addr_is_null(addr) ||
      (!tor_addr_is_v4(addr) && !tor_addr_is_v6(addr)) ||
      !the_nodelist || !the_nodelist->node_addrs ||
      !the_nodelist->reentry_set) {
    return;
  }
  address_set_add(the_nodelist->node_addrs, addr);
  if (or_port != 0) {
    digestmap_set(the_nodelist->reentry_set,
                  build_addr_port_item(addr, or_port), (void*) 1);
  }
  if (dir_port != 0) {
    digestmap_set(the_nodelist->reentry_set,
                  build_addr_port_item(addr, dir_port), (void*) 1);
  }
}

/** Return true if <b>addr</b> is the address of some node in the nodelist.
 * If not, probably return false. */
int
nodelist_probably_contains_address(const tor_addr_t *addr)
{
  if (BUG(!addr))
    return 0;

  if (!the_nodelist || !the_nodelist->node_addrs)
    return 0;

  return address_set_probably_contains(the_nodelist->node_addrs, addr);
}

/** Return true if <b>addr</b> is the address of some node in the nodelist and
 * corresponds also to the given port. If not, probably return false. */
bool
nodelist_reentry_contains(const tor_addr_t *addr, uint16_t port)
{
  if (BUG(!addr) || BUG(!port))
    return false;

  if (!the_nodelist || !the_nodelist->reentry_set)
    return false;

  return digestmap_get(the_nodelist->reentry_set,
                       build_addr_port_item(addr, port)) != NULL;
}

/** Add <b>ri</b> to an appropriate node in the nodelist.  If we replace an
 * old routerinfo, and <b>ri_old_out</b> is not NULL, set *<b>ri_old_out</b>
 * to the previous routerinfo.
 */
node_t *
nodelist_set_routerinfo(routerinfo_t *ri, routerinfo_t **ri_old_out)
{
  node_t *node;
  const char *id_digest;
  int had_router = 0;
  tor_assert(ri);

  init_nodelist();
  id_digest = ri->cache_info.identity_digest;
  node = node_get_or_create(id_digest);

  node_remove_from_ed25519_map(node);

  if (node->ri) {
    if (!routers_have_same_or_addrs(node->ri, ri)) {
      node_addrs_changed(node);
    }
    had_router = 1;
    if (ri_old_out)
      *ri_old_out = node->ri;
  } else {
    if (ri_old_out)
      *ri_old_out = NULL;
  }
  node->ri = ri;

  node_add_to_ed25519_map(node);

  if (node->country == -1)
    node_set_country(node);

  if (authdir_mode(get_options()) && !had_router) {
    const char *discard=NULL;
    uint32_t status = dirserv_router_get_status(ri, &discard, LOG_INFO);
    dirserv_set_node_flags_from_authoritative_status(node, status);
  }

  /* Setting the HSDir index requires the ed25519 identity key which can
   * only be found either in the ri or md. This is why this is called here.
   * Only nodes supporting HSDir=2 protocol version needs this index. */
  if (node->rs && node->rs->pv.supports_v3_hsdir) {
    node_set_hsdir_index(node,
                         networkstatus_get_latest_consensus());
  }

  node_add_to_address_set(node);

  return node;
}

/** Set the appropriate node_t to use <b>md</b> as its microdescriptor.
 *
 * Called when a new microdesc has arrived and the usable consensus flavor
 * is "microdesc".
 **/
node_t *
nodelist_add_microdesc(microdesc_t *md)
{
  networkstatus_t *ns =
    networkstatus_get_latest_consensus_by_flavor(FLAV_MICRODESC);
  const routerstatus_t *rs;
  node_t *node;
  if (ns == NULL)
    return NULL;
  init_nodelist();

  /* Microdescriptors don't carry an identity digest, so we need to figure
   * it out by looking up the routerstatus. */
  rs = router_get_consensus_status_by_descriptor_digest(ns, md->digest);
  if (rs == NULL)
    return NULL;
  node = node_get_mutable_by_id(rs->identity_digest);
  if (node == NULL)
    return NULL;

  node_remove_from_ed25519_map(node);
  if (node->md)
    node->md->held_by_nodes--;

  node->md = md;
  md->held_by_nodes++;
  /* Setting the HSDir index requires the ed25519 identity key which can
   * only be found either in the ri or md. This is why this is called here.
   * Only nodes supporting HSDir=2 protocol version needs this index. */
  if (rs->pv.supports_v3_hsdir) {
    node_set_hsdir_index(node, ns);
  }
  node_add_to_ed25519_map(node);
  node_add_to_address_set(node);

  return node;
}

/* Default value. */
#define ESTIMATED_ADDRESS_PER_NODE 2

/* Return the estimated number of address per node_t. This is used for the
 * size of the bloom filter in the nodelist (node_addrs). */
MOCK_IMPL(int,
get_estimated_address_per_node, (void))
{
  return ESTIMATED_ADDRESS_PER_NODE;
}

/** Tell the nodelist that the current usable consensus is <b>ns</b>.
 * This makes the nodelist change all of the routerstatus entries for
 * the nodes, drop nodes that no longer have enough info to get used,
 * and grab microdescriptors into nodes as appropriate.
 */
void
nodelist_set_consensus(const networkstatus_t *ns)
{
  const or_options_t *options = get_options();
  int authdir = authdir_mode_v3(options);

  init_nodelist();
  if (ns->flavor == FLAV_MICRODESC)
    (void) get_microdesc_cache(); /* Make sure it exists first. */

  SMARTLIST_FOREACH(the_nodelist->nodes, node_t *, node,
                    node->rs = NULL);

  /* Conservatively estimate that every node will have 2 addresses (v4 and
   * v6). Then we add the number of configured trusted authorities we have. */
  int estimated_addresses = smartlist_len(ns->routerstatus_list) *
                            get_estimated_address_per_node();
  estimated_addresses += (get_n_authorities(V3_DIRINFO | BRIDGE_DIRINFO) *
                          get_estimated_address_per_node());
  /* Clear our sets because we will repopulate them with what this new
   * consensus contains. */
  address_set_free(the_nodelist->node_addrs);
  the_nodelist->node_addrs = address_set_new(estimated_addresses);
  digestmap_free(the_nodelist->reentry_set, NULL);
  the_nodelist->reentry_set = digestmap_new();

  SMARTLIST_FOREACH_BEGIN(ns->routerstatus_list, routerstatus_t *, rs) {
    node_t *node = node_get_or_create(rs->identity_digest);
    node->rs = rs;
    if (ns->flavor == FLAV_MICRODESC) {
      if (node->md == NULL ||
          tor_memneq(node->md->digest,rs->descriptor_digest,DIGEST256_LEN)) {
        node_remove_from_ed25519_map(node);
        if (node->md)
          node->md->held_by_nodes--;
        node->md = microdesc_cache_lookup_by_digest256(NULL,
                                                       rs->descriptor_digest);
        if (node->md)
          node->md->held_by_nodes++;
        node_add_to_ed25519_map(node);
      }
    }

    if (rs->pv.supports_v3_hsdir) {
      node_set_hsdir_index(node, ns);
    }
    node_set_country(node);

    /* If we're not an authdir, believe others. */
    if (!authdir) {
      node->is_valid = rs->is_valid;
      node->is_running = rs->is_flagged_running;
      node->is_fast = rs->is_fast;
      node->is_stable = rs->is_stable;
      node->is_possible_guard = rs->is_possible_guard;
      node->is_exit = rs->is_exit;
      node->is_bad_exit = rs->is_bad_exit;
      node->is_hs_dir = rs->is_hs_dir;
      node->ipv6_preferred = 0;
      if (reachable_addr_prefer_ipv6_orport(options) &&
          (tor_addr_is_null(&rs->ipv6_addr) == 0 ||
           (node->md && tor_addr_is_null(&node->md->ipv6_addr) == 0)))
        node->ipv6_preferred = 1;
    }

  } SMARTLIST_FOREACH_END(rs);

  nodelist_purge();

  /* Now add all the nodes we have to the address set. */
  SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) {
    node_add_to_address_set(node);
  } SMARTLIST_FOREACH_END(node);
  /* Then, add all trusted configured directories. Some might not be in the
   * consensus so make sure we know them. */
  dirlist_add_trusted_dir_addresses();

  if (! authdir) {
    SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) {
      /* We have no routerstatus for this router. Clear flags so we can skip
       * it, maybe.*/
      if (!node->rs) {
        tor_assert(node->ri); /* if it had only an md, or nothing, purge
                               * would have removed it. */
        if (node->ri->purpose == ROUTER_PURPOSE_GENERAL) {
          /* Clear all flags. */
          node->is_valid = node->is_running = node->is_hs_dir =
            node->is_fast = node->is_stable =
            node->is_possible_guard = node->is_exit =
            node->is_bad_exit = node->ipv6_preferred = 0;
        }
      }
    } SMARTLIST_FOREACH_END(node);
  }

  /* If the consensus is live, note down the consensus valid-after that formed
   * the nodelist. */
  if (networkstatus_is_live(ns, approx_time())) {
    the_nodelist->live_consensus_valid_after = ns->valid_after;
  }
}

/** Return 1 iff <b>node</b> has Exit flag and no BadExit flag.
 * Otherwise, return 0.
 */
int
node_is_good_exit(const node_t *node)
{
  return node->is_exit && ! node->is_bad_exit;
}

/** Helper: return true iff a node has a usable amount of information*/
static inline int
node_is_usable(const node_t *node)
{
  return (node->rs) || (node->ri);
}

/** Tell the nodelist that <b>md</b> is no longer a microdescriptor for the
 * node with <b>identity_digest</b>. */
void
nodelist_remove_microdesc(const char *identity_digest, microdesc_t *md)
{
  node_t *node = node_get_mutable_by_id(identity_digest);
  if (node && node->md == md) {
    node->md = NULL;
    md->held_by_nodes--;
    if (! node_get_ed25519_id(node)) {
      node_remove_from_ed25519_map(node);
    }
  }
}

/** Tell the nodelist that <b>ri</b> is no longer in the routerlist. */
void
nodelist_remove_routerinfo(routerinfo_t *ri)
{
  node_t *node = node_get_mutable_by_id(ri->cache_info.identity_digest);
  if (node && node->ri == ri) {
    node->ri = NULL;
    if (! node_is_usable(node)) {
      nodelist_drop_node(node, 1);
      node_free(node);
    }
  }
}

/** Remove <b>node</b> from the nodelist.  (Asserts that it was there to begin
 * with.) */
static void
nodelist_drop_node(node_t *node, int remove_from_ht)
{
  node_t *tmp;
  int idx;
  if (remove_from_ht) {
    tmp = HT_REMOVE(nodelist_map, &the_nodelist->nodes_by_id, node);
    tor_assert(tmp == node);
  }
  node_remove_from_ed25519_map(node);

  idx = node->nodelist_idx;
  tor_assert(idx >= 0);

  tor_assert(node == smartlist_get(the_nodelist->nodes, idx));
  smartlist_del(the_nodelist->nodes, idx);
  if (idx < smartlist_len(the_nodelist->nodes)) {
    tmp = smartlist_get(the_nodelist->nodes, idx);
    tmp->nodelist_idx = idx;
  }
  node->nodelist_idx = -1;
}

/** Return a newly allocated smartlist of the nodes that have <b>md</b> as
 * their microdescriptor. */
smartlist_t *
nodelist_find_nodes_with_microdesc(const microdesc_t *md)
{
  smartlist_t *result = smartlist_new();

  if (the_nodelist == NULL)
    return result;

  SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) {
    if (node->md == md) {
      smartlist_add(result, node);
    }
  } SMARTLIST_FOREACH_END(node);

  return result;
}

/** Release storage held by <b>node</b>  */
static void
node_free_(node_t *node)
{
  if (!node)
    return;
  if (node->md)
    node->md->held_by_nodes--;
  tor_assert(node->nodelist_idx == -1);
  tor_free(node);
}

/** Remove all entries from the nodelist that don't have enough info to be
 * usable for anything. */
void
nodelist_purge(void)
{
  node_t **iter;
  if (PREDICT_UNLIKELY(the_nodelist == NULL))
    return;

  /* Remove the non-usable nodes. */
  for (iter = HT_START(nodelist_map, &the_nodelist->nodes_by_id); iter; ) {
    node_t *node = *iter;

    if (node->md && !node->rs) {
      /* An md is only useful if there is an rs. */
      node->md->held_by_nodes--;
      node->md = NULL;
    }

    if (node_is_usable(node)) {
      iter = HT_NEXT(nodelist_map, &the_nodelist->nodes_by_id, iter);
    } else {
      iter = HT_NEXT_RMV(nodelist_map, &the_nodelist->nodes_by_id, iter);
      nodelist_drop_node(node, 0);
      node_free(node);
    }
  }
  nodelist_assert_ok();
}

/** Release all storage held by the nodelist. */
void
nodelist_free_all(void)
{
  if (PREDICT_UNLIKELY(the_nodelist == NULL))
    return;

  HT_CLEAR(nodelist_map, &the_nodelist->nodes_by_id);
  HT_CLEAR(nodelist_ed_map, &the_nodelist->nodes_by_ed_id);
  SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) {
    node->nodelist_idx = -1;
    node_free(node);
  } SMARTLIST_FOREACH_END(node);

  smartlist_free(the_nodelist->nodes);

  address_set_free(the_nodelist->node_addrs);
  the_nodelist->node_addrs = NULL;
  digestmap_free(the_nodelist->reentry_set, NULL);
  the_nodelist->reentry_set = NULL;

  tor_free(the_nodelist);
}

/** Check that the nodelist is internally consistent, and consistent with
 * the directory info it's derived from.
 */
void
nodelist_assert_ok(void)
{
  routerlist_t *rl = router_get_routerlist();
  networkstatus_t *ns = networkstatus_get_latest_consensus();
  digestmap_t *dm;

  if (!the_nodelist)
    return;

  dm = digestmap_new();

  /* every routerinfo in rl->routers should be in the nodelist. */
  if (rl) {
    SMARTLIST_FOREACH_BEGIN(rl->routers, routerinfo_t *, ri) {
      const node_t *node = node_get_by_id(ri->cache_info.identity_digest);
      tor_assert(node && node->ri == ri);
      tor_assert(fast_memeq(ri->cache_info.identity_digest,
                             node->identity, DIGEST_LEN));
      tor_assert(! digestmap_get(dm, node->identity));
      digestmap_set(dm, node->identity, (void*)node);
    } SMARTLIST_FOREACH_END(ri);
  }

  /* every routerstatus in ns should be in the nodelist */
  if (ns) {
    SMARTLIST_FOREACH_BEGIN(ns->routerstatus_list, routerstatus_t *, rs) {
      const node_t *node = node_get_by_id(rs->identity_digest);
      tor_assert(node && node->rs == rs);
      tor_assert(fast_memeq(rs->identity_digest, node->identity, DIGEST_LEN));
      digestmap_set(dm, node->identity, (void*)node);
      if (ns->flavor == FLAV_MICRODESC) {
        /* If it's a microdesc consensus, every entry that has a
         * microdescriptor should be in the nodelist.
         */
        microdesc_t *md =
          microdesc_cache_lookup_by_digest256(NULL, rs->descriptor_digest);
        tor_assert(md == node->md);
        if (md)
          tor_assert(md->held_by_nodes >= 1);
      }
    } SMARTLIST_FOREACH_END(rs);
  }

  /* The nodelist should have no other entries, and its entries should be
   * well-formed. */
  SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) {
    tor_assert(digestmap_get(dm, node->identity) != NULL);
    tor_assert(node_sl_idx == node->nodelist_idx);
  } SMARTLIST_FOREACH_END(node);

  /* Every node listed with an ed25519 identity should be listed by that
   * identity.
   */
  SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) {
    if (!ed25519_public_key_is_zero(&node->ed25519_id)) {
      tor_assert(node == node_get_by_ed25519_id(&node->ed25519_id));
    }
  } SMARTLIST_FOREACH_END(node);

  node_t **idx;
  HT_FOREACH(idx, nodelist_ed_map, &the_nodelist->nodes_by_ed_id) {
    node_t *node = *idx;
    tor_assert(node == node_get_by_ed25519_id(&node->ed25519_id));
  }

  tor_assert((long)smartlist_len(the_nodelist->nodes) ==
             (long)HT_SIZE(&the_nodelist->nodes_by_id));

  tor_assert((long)smartlist_len(the_nodelist->nodes) >=
             (long)HT_SIZE(&the_nodelist->nodes_by_ed_id));

  digestmap_free(dm, NULL);
}

/** Ensure that the nodelist has been created with the most recent consensus.
 *  If that's not the case, make it so.  */
void
nodelist_ensure_freshness(const networkstatus_t *ns)
{
  tor_assert(ns);

  /* We don't even have a nodelist: this is a NOP. */
  if (!the_nodelist) {
    return;
  }

  if (the_nodelist->live_consensus_valid_after != ns->valid_after) {
    log_info(LD_GENERAL, "Nodelist was not fresh: rebuilding. (%d / %d)",
             (int) the_nodelist->live_consensus_valid_after,
             (int) ns->valid_after);
    nodelist_set_consensus(ns);
  }
}
/** Return a list of a node_t * for every node we know about.  The caller
 * MUST NOT modify the list. (You can set and clear flags in the nodes if
 * you must, but you must not add or remove nodes.) */
MOCK_IMPL(const smartlist_t *,
nodelist_get_list,(void))
{
  init_nodelist();
  return the_nodelist->nodes;
}

/** Given a hex-encoded nickname of the format DIGEST, $DIGEST, $DIGEST=name,
 * or $DIGEST~name, return the node with the matching identity digest and
 * nickname (if any).  Return NULL if no such node exists, or if <b>hex_id</b>
 * is not well-formed. DOCDOC flags */
const node_t *
node_get_by_hex_id(const char *hex_id, unsigned flags)
{
  char digest_buf[DIGEST_LEN];
  char nn_buf[MAX_NICKNAME_LEN+1];
  char nn_char='\0';

  (void) flags; // XXXX

  if (hex_digest_nickname_decode(hex_id, digest_buf, &nn_char, nn_buf)==0) {
    const node_t *node = node_get_by_id(digest_buf);
    if (!node)
      return NULL;
    if (nn_char == '=') {
      /* "=" indicates a Named relay, but there aren't any of those now. */
      return NULL;
    }
    return node;
  }

  return NULL;
}

/** Given a nickname (possibly verbose, possibly a hexadecimal digest), return
 * the corresponding node_t, or NULL if none exists. Warn the user if they
 * have specified a router by nickname, unless the NNF_NO_WARN_UNNAMED bit is
 * set in <b>flags</b>. */
MOCK_IMPL(const node_t *,
node_get_by_nickname,(const char *nickname, unsigned flags))
{
  const int warn_if_unnamed = !(flags & NNF_NO_WARN_UNNAMED);

  if (!the_nodelist)
    return NULL;

  /* Handle these cases: DIGEST, $DIGEST, $DIGEST=name, $DIGEST~name. */
  {
    const node_t *node;
    if ((node = node_get_by_hex_id(nickname, flags)) != NULL)
      return node;
  }

  if (!strcasecmp(nickname, UNNAMED_ROUTER_NICKNAME))
    return NULL;

  /* Okay, so the name is not canonical for anybody. */
  {
    smartlist_t *matches = smartlist_new();
    const node_t *choice = NULL;

    SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) {
      if (!strcasecmp(node_get_nickname(node), nickname))
        smartlist_add(matches, node);
    } SMARTLIST_FOREACH_END(node);

    if (smartlist_len(matches)>1 && warn_if_unnamed) {
      int any_unwarned = 0;
      SMARTLIST_FOREACH_BEGIN(matches, node_t *, node) {
        if (!node->name_lookup_warned) {
          node->name_lookup_warned = 1;
          any_unwarned = 1;
        }
      } SMARTLIST_FOREACH_END(node);

      if (any_unwarned) {
        log_warn(LD_CONFIG, "There are multiple matches for the name %s. "
                 "Choosing one arbitrarily.", nickname);
      }
    } else if (smartlist_len(matches)==1 && warn_if_unnamed) {
      char fp[HEX_DIGEST_LEN+1];
      node_t *node = smartlist_get(matches, 0);
      if (! node->name_lookup_warned) {
        base16_encode(fp, sizeof(fp), node->identity, DIGEST_LEN);
        log_warn(LD_CONFIG,
                 "You specified a relay \"%s\" by name, but nicknames can be "
                 "used by any relay, not just the one you meant. "
                 "To make sure you get the same relay in the future, refer "
                 "to it by key, as \"$%s\".", nickname, fp);
        node->name_lookup_warned = 1;
      }
    }

    if (smartlist_len(matches))
      choice = smartlist_get(matches, 0);

    smartlist_free(matches);
    return choice;
  }
}

/** Return the Ed25519 identity key for the provided node, or NULL if it
 * doesn't have one. */
MOCK_IMPL(const ed25519_public_key_t *,
node_get_ed25519_id,(const node_t *node))
{
  const ed25519_public_key_t *ri_pk = NULL;
  const ed25519_public_key_t *md_pk = NULL;

  if (node->ri) {
    if (node->ri->cache_info.signing_key_cert) {
      ri_pk = &node->ri->cache_info.signing_key_cert->signing_key;
      /* Checking whether routerinfo ed25519 is all zero.
       * Our descriptor parser should make sure this never happens. */
      if (BUG(ed25519_public_key_is_zero(ri_pk)))
        ri_pk = NULL;
    }
  }

  if (node->md) {
    if (node->md->ed25519_identity_pkey) {
      md_pk = node->md->ed25519_identity_pkey;
      /* Checking whether microdesc ed25519 is all zero.
       * Our descriptor parser should make sure this never happens. */
      if (BUG(ed25519_public_key_is_zero(md_pk)))
        md_pk = NULL;
    }
  }

  if (ri_pk && md_pk) {
    if (ed25519_pubkey_eq(ri_pk, md_pk)) {
      return ri_pk;
    } else {
      /* This can happen if the relay gets flagged NoEdConsensus which will be
       * triggered on all relays of the network. Thus a protocol warning. */
      log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
             "Inconsistent ed25519 identities in the nodelist");
      return NULL;
    }
  } else if (ri_pk) {
    return ri_pk;
  } else {
    return md_pk;
  }
}

/** Return true iff this node's Ed25519 identity matches <b>id</b>.
 * (An absent Ed25519 identity matches NULL or zero.) */
int
node_ed25519_id_matches(const node_t *node, const ed25519_public_key_t *id)
{
  const ed25519_public_key_t *node_id = node_get_ed25519_id(node);
  if (node_id == NULL || ed25519_public_key_is_zero(node_id)) {
    return id == NULL || ed25519_public_key_is_zero(id);
  } else {
    return id && ed25519_pubkey_eq(node_id, id);
  }
}

/** Dummy object that should be unreturnable.  Used to ensure that
 * node_get_protover_summary_flags() always returns non-NULL. */
static const protover_summary_flags_t zero_protover_flags = {
  0,0,0,0,0,0,0,0,0,0,0,0
};

/** Return the protover_summary_flags for a given node. */
static const protover_summary_flags_t *
node_get_protover_summary_flags(const node_t *node)
{
  if (node->rs) {
    return &node->rs->pv;
  } else if (node->ri) {
    return &node->ri->pv;
  } else {
    /* This should be impossible: every node should have a routerstatus or a
     * router descriptor or both. But just in case we've messed up somehow,
     * return a nice empty set of flags to indicate "this node supports
     * nothing." */
    tor_assert_nonfatal_unreached_once();
    return &zero_protover_flags;
  }
}

/** Return true iff <b>node</b> supports authenticating itself
 * by ed25519 ID during the link handshake.  If <b>compatible_with_us</b>,
 * it needs to be using a link authentication method that we understand.
 * If not, any plausible link authentication method will do. */
MOCK_IMPL(bool,
node_supports_ed25519_link_authentication,(const node_t *node,
                                           bool compatible_with_us))
{
  if (! node_get_ed25519_id(node))
    return 0;

  const protover_summary_flags_t *pv = node_get_protover_summary_flags(node);

  if (compatible_with_us)
    return pv->supports_ed25519_link_handshake_compat;
  else
    return pv->supports_ed25519_link_handshake_any;
}

/** Return true iff <b>node</b> supports the hidden service directory version
 * 3 protocol (proposal 224). */
bool
node_supports_v3_hsdir(const node_t *node)
{
  tor_assert(node);

  return node_get_protover_summary_flags(node)->supports_v3_hsdir;
}

/** Return true iff <b>node</b> supports ed25519 authentication as an hidden
 * service introduction point.*/
bool
node_supports_ed25519_hs_intro(const node_t *node)
{
  tor_assert(node);

  return node_get_protover_summary_flags(node)->supports_ed25519_hs_intro;
}

/** Return true iff <b>node</b> can be a rendezvous point for hidden
 * service version 3 (HSRend=2). */
bool
node_supports_v3_rendezvous_point(const node_t *node)
{
  tor_assert(node);

  /* We can't use a v3 rendezvous point without the curve25519 onion pk. */
  if (!node_get_curve25519_onion_key(node)) {
    return 0;
  }

  return node_get_protover_summary_flags(node)->supports_v3_rendezvous_point;
}

/** Return true iff <b>node</b> supports the DoS ESTABLISH_INTRO cell
 * extension. */
bool
node_supports_establish_intro_dos_extension(const node_t *node)
{
  tor_assert(node);

  return node_get_protover_summary_flags(node)->
                           supports_establish_intro_dos_extension;
}

/** Return true iff <b>node</b> can initiate IPv6 extends (Relay=3).
 *
 * This check should only be performed by client path selection code.
 *
 * Extending relays should check their own IPv6 support using
 * router_can_extend_over_ipv6(). Like other extends, they should not verify
 * the link specifiers in the extend cell against the consensus, because it
 * may be out of date. */
bool
node_supports_initiating_ipv6_extends(const node_t *node)
{
  tor_assert(node);

  /* Relays can't initiate an IPv6 extend, unless they have an IPv6 ORPort. */
  if (!node_has_ipv6_orport(node)) {
    return 0;
  }

  /* Initiating relays also need to support the relevant protocol version. */
  return
    node_get_protover_summary_flags(node)->supports_initiating_ipv6_extends;
}

/** Return true iff <b>node</b> can accept IPv6 extends (Relay=2 or Relay=3)
 * from other relays. If <b>need_canonical_ipv6_conn</b> is true, also check
 * if the relay supports canonical IPv6 connections (Relay=3 only).
 *
 * This check should only be performed by client path selection code.
 */
bool
node_supports_accepting_ipv6_extends(const node_t *node,
                                            bool need_canonical_ipv6_conn)
{
  tor_assert(node);

  /* Relays can't accept an IPv6 extend, unless they have an IPv6 ORPort. */
  if (!node_has_ipv6_orport(node)) {
    return 0;
  }

  /* Accepting relays also need to support the relevant protocol version. */
  if (need_canonical_ipv6_conn) {
    return
      node_get_protover_summary_flags(node)->supports_canonical_ipv6_conns;
  } else {
    return
      node_get_protover_summary_flags(node)->supports_accepting_ipv6_extends;
  }
}

/** Return the RSA ID key's SHA1 digest for the provided node. */
const uint8_t *
node_get_rsa_id_digest(const node_t *node)
{
  tor_assert(node);
  return (const uint8_t*)node->identity;
}

/* Returns a new smartlist with all possible link specifiers from node:
 *  - legacy ID is mandatory thus MUST be present in node;
 *  - include ed25519 link specifier if present in the node, and the node
 *    supports ed25519 link authentication, and:
 *    - if direct_conn is true, its link versions are compatible with us,
 *    - if direct_conn is false, regardless of its link versions;
 *  - include IPv4 link specifier, if the primary address is not IPv4, log a
 *    BUG() warning, and return an empty smartlist;
 *  - include IPv6 link specifier if present in the node.
 *
 * If node is NULL, returns an empty smartlist.
 *
 * The smartlist must be freed using link_specifier_smartlist_free(). */
MOCK_IMPL(smartlist_t *,
node_get_link_specifier_smartlist,(const node_t *node, bool direct_conn))
{
  link_specifier_t *ls;
  tor_addr_port_t ap;
  smartlist_t *lspecs = smartlist_new();

  if (!node)
    return lspecs;

  /* Get the relay's IPv4 address. */
  node_get_prim_orport(node, &ap);

  /* We expect the node's primary address to be a valid IPv4 address.
   * This conforms to the protocol, which requires either an IPv4 or IPv6
   * address (or both). */
  if (BUG(!tor_addr_is_v4(&ap.addr)) ||
      BUG(!tor_addr_port_is_valid_ap(&ap, 0))) {
    return lspecs;
  }

  ls = link_specifier_new();
  link_specifier_set_ls_type(ls, LS_IPV4);
  link_specifier_set_un_ipv4_addr(ls, tor_addr_to_ipv4h(&ap.addr));
  link_specifier_set_un_ipv4_port(ls, ap.port);
  /* Four bytes IPv4 and two bytes port. */
  link_specifier_set_ls_len(ls, sizeof(ap.addr.addr.in_addr) +
                            sizeof(ap.port));
  smartlist_add(lspecs, ls);

  /* Legacy ID is mandatory and will always be present in node. */
  ls = link_specifier_new();
  link_specifier_set_ls_type(ls, LS_LEGACY_ID);
  memcpy(link_specifier_getarray_un_legacy_id(ls), node->identity,
         link_specifier_getlen_un_legacy_id(ls));
  link_specifier_set_ls_len(ls, link_specifier_getlen_un_legacy_id(ls));
  smartlist_add(lspecs, ls);

  /* ed25519 ID is only included if the node has it, and the node declares a
   protocol version that supports ed25519 link authentication.
   If direct_conn is true, we also require that the node's link version is
   compatible with us. (Otherwise, we will be sending the ed25519 key
   to another tor, which may support different link versions.) */
  if (!ed25519_public_key_is_zero(&node->ed25519_id) &&
      node_supports_ed25519_link_authentication(node, direct_conn)) {
    ls = link_specifier_new();
    link_specifier_set_ls_type(ls, LS_ED25519_ID);
    memcpy(link_specifier_getarray_un_ed25519_id(ls), &node->ed25519_id,
           link_specifier_getlen_un_ed25519_id(ls));
    link_specifier_set_ls_len(ls, link_specifier_getlen_un_ed25519_id(ls));
    smartlist_add(lspecs, ls);
  }

  /* Check for IPv6. If so, include it as well. */
  if (node_has_ipv6_orport(node)) {
    ls = link_specifier_new();
    node_get_pref_ipv6_orport(node, &ap);
    link_specifier_set_ls_type(ls, LS_IPV6);
    size_t addr_len = link_specifier_getlen_un_ipv6_addr(ls);
    const uint8_t *in6_addr = tor_addr_to_in6_addr8(&ap.addr);
    uint8_t *ipv6_array = link_specifier_getarray_un_ipv6_addr(ls);
    memcpy(ipv6_array, in6_addr, addr_len);
    link_specifier_set_un_ipv6_port(ls, ap.port);
    /* Sixteen bytes IPv6 and two bytes port. */
    link_specifier_set_ls_len(ls, addr_len + sizeof(ap.port));
    smartlist_add(lspecs, ls);
  }

  return lspecs;
}

/* Free a link specifier list. */
void
link_specifier_smartlist_free_(smartlist_t *ls_list)
{
  if (!ls_list)
    return;

  SMARTLIST_FOREACH(ls_list, link_specifier_t *, lspec,
                    link_specifier_free(lspec));
  smartlist_free(ls_list);
}

/** Return the nickname of <b>node</b>, or NULL if we can't find one. */
const char *
node_get_nickname(const node_t *node)
{
  tor_assert(node);
  if (node->rs)
    return node->rs->nickname;
  else if (node->ri)
    return node->ri->nickname;
  else
    return NULL;
}

/** Return true iff <b>node</b> appears to be a directory authority or
 * directory cache */
int
node_is_dir(const node_t *node)
{
  if (node->rs) {
    routerstatus_t * rs = node->rs;
    /* This is true if supports_tunnelled_dir_requests is true which
     * indicates that we support directory request tunnelled or through the
     * DirPort. */
    return rs->is_v2_dir;
  } else if (node->ri) {
    routerinfo_t * ri = node->ri;
    /* Both tunnelled request is supported or DirPort is set. */
    return ri->supports_tunnelled_dir_requests;
  } else {
    return 0;
  }
}

/** Return true iff <b>node</b> has either kind of descriptor -- that
 * is, a routerdescriptor or a microdescriptor.
 *
 * You should probably use node_has_preferred_descriptor() instead.
 **/
int
node_has_any_descriptor(const node_t *node)
{
  return (node->ri ||
          (node->rs && node->md));
}

/** Return true iff <b>node</b> has the kind of descriptor we would prefer to
 * use for it, given our configuration and how we intend to use the node.
 *
 * If <b>for_direct_connect</b> is true, we intend to connect to the node
 * directly, as the first hop of a circuit; otherwise, we intend to connect to
 * it indirectly, or use it as if we were connecting to it indirectly. */
int
node_has_preferred_descriptor(const node_t *node,
                              int for_direct_connect)
{
  const int is_bridge = node_is_a_configured_bridge(node);
  const int we_use_mds = we_use_microdescriptors_for_circuits(get_options());

  if ((is_bridge && for_direct_connect) || !we_use_mds) {
    /* We need an ri in this case. */
    if (!node->ri)
      return 0;
  } else {
    /* Otherwise we need an rs and an md. */
    if (node->rs == NULL || node->md == NULL)
      return 0;
  }

  return 1;
}

/** Return the router_purpose of <b>node</b>. */
int
node_get_purpose(const node_t *node)
{
  if (node->ri)
    return node->ri->purpose;
  else
    return ROUTER_PURPOSE_GENERAL;
}

/** Compute the verbose ("extended") nickname of <b>node</b> and store it
 * into the MAX_VERBOSE_NICKNAME_LEN+1 character buffer at
 * <b>verbose_name_out</b> */
void
node_get_verbose_nickname(const node_t *node,
                          char *verbose_name_out)
{
  const char *nickname = node_get_nickname(node);
  verbose_name_out[0] = '$';
  base16_encode(verbose_name_out+1, HEX_DIGEST_LEN+1, node->identity,
                DIGEST_LEN);
  if (!nickname)
    return;
  verbose_name_out[1+HEX_DIGEST_LEN] = '~';
  strlcpy(verbose_name_out+1+HEX_DIGEST_LEN+1, nickname, MAX_NICKNAME_LEN+1);
}

/** Compute the verbose ("extended") nickname of node with
 * given <b>id_digest</b> and store it into the MAX_VERBOSE_NICKNAME_LEN+1
 * character buffer at <b>verbose_name_out</b>
 *
 * If node_get_by_id() returns NULL, base 16 encoding of
 * <b>id_digest</b> is returned instead. */
void
node_get_verbose_nickname_by_id(const char *id_digest,
                                char *verbose_name_out)
{
  const node_t *node = node_get_by_id(id_digest);
  if (!node) {
    verbose_name_out[0] = '$';
    base16_encode(verbose_name_out+1, HEX_DIGEST_LEN+1, id_digest, DIGEST_LEN);
  } else {
    node_get_verbose_nickname(node, verbose_name_out);
  }
}

/** Return true iff it seems that <b>node</b> allows circuits to exit
 * through it directlry from the client. */
int
node_allows_single_hop_exits(const node_t *node)
{
  if (node && node->ri)
    return node->ri->allow_single_hop_exits;
  else
    return 0;
}

/** Return true iff it seems that <b>node</b> has an exit policy that doesn't
 * actually permit anything to exit, or we don't know its exit policy */
int
node_exit_policy_rejects_all(const node_t *node)
{
  if (node->rejects_all)
    return 1;

  if (node->ri)
    return node->ri->policy_is_reject_star;
  else if (node->md)
    return node->md->policy_is_reject_star;
  else
    return 1;
}

/** Return true iff the exit policy for <b>node</b> is such that we can treat
 * rejecting an address of type <b>family</b> unexpectedly as a sign of that
 * node's failure. */
int
node_exit_policy_is_exact(const node_t *node, sa_family_t family)
{
  if (family == AF_UNSPEC) {
    return 1; /* Rejecting an address but not telling us what address
               * is a bad sign. */
  } else if (family == AF_INET) {
    return node->ri != NULL;
  } else if (family == AF_INET6) {
    return 0;
  }
  tor_fragile_assert();
  return 1;
}

/* Check if the "addr" and port_field fields from r are a valid non-listening
 * address/port. If so, set valid to true and add a newly allocated
 * tor_addr_port_t containing "addr" and port_field to sl.
 * "addr" is an IPv4 host-order address and port_field is a uint16_t.
 * r is typically a routerinfo_t or routerstatus_t.
 */
#define SL_ADD_NEW_AP(r, addr_field, port_field, sl, valid)             \
  STMT_BEGIN                                                            \
    if (tor_addr_port_is_valid(&(r)->addr_field, (r)->port_field, 0)) { \
      valid = 1;                                                        \
      tor_addr_port_t *ap = tor_addr_port_new(&(r)->addr_field,         \
                                              (r)->port_field);         \
      smartlist_add((sl), ap);                                          \
    }                                                                   \
  STMT_END

/** Return list of tor_addr_port_t with all OR ports (in the sense IP
 * addr + TCP port) for <b>node</b>.  Caller must free all elements
 * using tor_free() and free the list using smartlist_free().
 *
 * XXX this is potentially a memory fragmentation hog -- if on
 * critical path consider the option of having the caller allocate the
 * memory
 */
smartlist_t *
node_get_all_orports(const node_t *node)
{
  smartlist_t *sl = smartlist_new();
  int valid = 0;

  /* Find a valid IPv4 address and port */
  if (node->ri != NULL) {
    SL_ADD_NEW_AP(node->ri, ipv4_addr, ipv4_orport, sl, valid);
  }

  /* If we didn't find a valid address/port in the ri, try the rs */
  if (!valid && node->rs != NULL) {
    SL_ADD_NEW_AP(node->rs, ipv4_addr, ipv4_orport, sl, valid);
  }

  /* Find a valid IPv6 address and port */
  valid = 0;
  if (node->ri != NULL) {
    SL_ADD_NEW_AP(node->ri, ipv6_addr, ipv6_orport, sl, valid);
  }

  if (!valid && node->rs != NULL) {
    SL_ADD_NEW_AP(node->rs, ipv6_addr, ipv6_orport, sl, valid);
  }

  if (!valid && node->md != NULL) {
    SL_ADD_NEW_AP(node->md, ipv6_addr, ipv6_orport, sl, valid);
  }

  return sl;
}

#undef SL_ADD_NEW_AP

/** Wrapper around node_get_prim_orport for backward
    compatibility.  */
void
node_get_addr(const node_t *node, tor_addr_t *addr_out)
{
  tor_addr_port_t ap;
  node_get_prim_orport(node, &ap);
  tor_addr_copy(addr_out, &ap.addr);
}

/** Return the IPv4 address for <b>node</b>, or NULL if none found. */
static const tor_addr_t *
node_get_prim_addr_ipv4(const node_t *node)
{
  /* Don't check the ORPort or DirPort, as this function isn't port-specific,
   * and the node might have a valid IPv4 address, yet have a zero
   * ORPort or DirPort.
   */
  if (node->ri && tor_addr_is_valid(&node->ri->ipv4_addr, 0)) {
    return &node->ri->ipv4_addr;
  } else if (node->rs && tor_addr_is_valid(&node->rs->ipv4_addr, 0)) {
    return &node->rs->ipv4_addr;
  }
  return NULL;
}

/** Copy a string representation of an IP address for <b>node</b> into
 * the <b>len</b>-byte buffer at <b>buf</b>.  */
void
node_get_address_string(const node_t *node, char *buf, size_t len)
{
  const tor_addr_t *ipv4_addr = node_get_prim_addr_ipv4(node);

  if (ipv4_addr) {
    tor_addr_to_str(buf, ipv4_addr, len, 0);
  } else if (len > 0) {
    buf[0] = '\0';
  }
}

/** Return <b>node</b>'s declared uptime, or -1 if it doesn't seem to have
 * one. */
long
node_get_declared_uptime(const node_t *node)
{
  if (node->ri)
    return node->ri->uptime;
  else
    return -1;
}

/** Return <b>node</b>'s platform string, or NULL if we don't know it. */
const char *
node_get_platform(const node_t *node)
{
  /* If we wanted, we could record the version in the routerstatus_t, since
   * the consensus lists it.  We don't, though, so this function just won't
   * work with microdescriptors. */
  if (node->ri)
    return node->ri->platform;
  else
    return NULL;
}

/** Return true iff <b>node</b> is one representing this router. */
int
node_is_me(const node_t *node)
{
  return router_digest_is_me(node->identity);
}

/* Does this node have a valid IPv6 address?
 * Prefer node_has_ipv6_orport() or node_has_ipv6_dirport() for
 * checking specific ports. */
int
node_has_ipv6_addr(const node_t *node)
{
  /* Don't check the ORPort or DirPort, as this function isn't port-specific,
   * and the node might have a valid IPv6 address, yet have a zero
   * ORPort or DirPort.
   */
  if (node->ri && tor_addr_is_valid(&node->ri->ipv6_addr, 0))
    return 1;
  if (node->rs && tor_addr_is_valid(&node->rs->ipv6_addr, 0))
    return 1;
  if (node->md && tor_addr_is_valid(&node->md->ipv6_addr, 0))
    return 1;

  return 0;
}

/* Does this node have a valid IPv6 ORPort? */
int
node_has_ipv6_orport(const node_t *node)
{
  tor_addr_port_t ipv6_orport;
  node_get_pref_ipv6_orport(node, &ipv6_orport);
  return tor_addr_port_is_valid_ap(&ipv6_orport, 0);
}

/* Does this node have a valid IPv6 DirPort? */
int
node_has_ipv6_dirport(const node_t *node)
{
  tor_addr_port_t ipv6_dirport;
  node_get_pref_ipv6_dirport(node, &ipv6_dirport);
  return tor_addr_port_is_valid_ap(&ipv6_dirport, 0);
}

/** Return 1 if we prefer the IPv6 address and OR TCP port of
 * <b>node</b>, else 0.
 *
 *  We prefer the IPv6 address if the router has an IPv6 address,
 *  and we can use IPv6 addresses, and:
 *  i) the node_t says that it prefers IPv6
 *  or
 *  ii) the router has no IPv4 OR address.
 *
 * If you don't have a node, consider looking it up.
 * If there is no node, use reachable_addr_prefer_ipv6_orport().
 */
int
node_ipv6_or_preferred(const node_t *node)
{
  const or_options_t *options = get_options();
  tor_addr_port_t ipv4_addr;
  node_assert_ok(node);

  /* XX/teor - node->ipv6_preferred is set from
   * reachable_addr_prefer_ipv6_orport() each time the consensus is loaded.
   */
  node_get_prim_orport(node, &ipv4_addr);
  if (!reachable_addr_use_ipv6(options)) {
    return 0;
  } else if (node->ipv6_preferred ||
             !tor_addr_port_is_valid_ap(&ipv4_addr, 0)) {
    return node_has_ipv6_orport(node);
  }
  return 0;
}

#define RETURN_IPV4_AP(r, port_field, ap_out)                               \
  STMT_BEGIN                                                                \
    if (r && tor_addr_port_is_valid(&(r)->ipv4_addr, (r)->port_field, 0)) { \
      tor_addr_copy(&(ap_out)->addr, &(r)->ipv4_addr);                      \
      (ap_out)->port = (r)->port_field;                                     \
    }                                                                       \
  STMT_END

/** Copy the primary (IPv4) OR port (IP address and TCP port) for <b>node</b>
 * into *<b>ap_out</b>. */
void
node_get_prim_orport(const node_t *node, tor_addr_port_t *ap_out)
{
  node_assert_ok(node);
  tor_assert(ap_out);

  /* Clear the address, as a safety precaution if calling functions ignore the
   * return value */
  tor_addr_make_null(&ap_out->addr, AF_INET);
  ap_out->port = 0;

  /* Check ri first, because rewrite_node_address_for_bridge() updates
   * node->ri with the configured bridge address. */

  RETURN_IPV4_AP(node->ri, ipv4_orport, ap_out);
  RETURN_IPV4_AP(node->rs, ipv4_orport, ap_out);
  /* Microdescriptors only have an IPv6 address */
}

/** Copy the preferred OR port (IP address and TCP port) for
 * <b>node</b> into *<b>ap_out</b>.  */
void
node_get_pref_orport(const node_t *node, tor_addr_port_t *ap_out)
{
  tor_assert(ap_out);

  if (node_ipv6_or_preferred(node)) {
    node_get_pref_ipv6_orport(node, ap_out);
  } else {
    /* the primary ORPort is always on IPv4 */
    node_get_prim_orport(node, ap_out);
  }
}

/** Copy the preferred IPv6 OR port (IP address and TCP port) for
 * <b>node</b> into *<b>ap_out</b>. */
void
node_get_pref_ipv6_orport(const node_t *node, tor_addr_port_t *ap_out)
{
  node_assert_ok(node);
  tor_assert(ap_out);
  memset(ap_out, 0, sizeof(*ap_out));

  /* Check ri first, because rewrite_node_address_for_bridge() updates
   * node->ri with the configured bridge address.
   * Prefer rs over md for consistency with the fascist_firewall_* functions.
   * Check if the address or port are valid, and try another alternative
   * if they are not. */

  if (node->ri && tor_addr_port_is_valid(&node->ri->ipv6_addr,
                                         node->ri->ipv6_orport, 0)) {
    tor_addr_copy(&ap_out->addr, &node->ri->ipv6_addr);
    ap_out->port = node->ri->ipv6_orport;
  } else if (node->rs && tor_addr_port_is_valid(&node->rs->ipv6_addr,
                                                 node->rs->ipv6_orport, 0)) {
    tor_addr_copy(&ap_out->addr, &node->rs->ipv6_addr);
    ap_out->port = node->rs->ipv6_orport;
  } else if (node->md && tor_addr_port_is_valid(&node->md->ipv6_addr,
                                                 node->md->ipv6_orport, 0)) {
    tor_addr_copy(&ap_out->addr, &node->md->ipv6_addr);
    ap_out->port = node->md->ipv6_orport;
  } else {
    tor_addr_make_null(&ap_out->addr, AF_INET6);
    ap_out->port = 0;
  }
}

/** Return 1 if we prefer the IPv6 address and Dir TCP port of
 * <b>node</b>, else 0.
 *
 *  We prefer the IPv6 address if the router has an IPv6 address,
 *  and we can use IPv6 addresses, and:
 *  i) the router has no IPv4 Dir address.
 *  or
 *  ii) our preference is for IPv6 Dir addresses.
 *
 * If there is no node, use reachable_addr_prefer_ipv6_dirport().
 */
int
node_ipv6_dir_preferred(const node_t *node)
{
  const or_options_t *options = get_options();
  tor_addr_port_t ipv4_addr;
  node_assert_ok(node);

  /* node->ipv6_preferred is set from reachable_addr_prefer_ipv6_orport(),
   * so we can't use it to determine DirPort IPv6 preference.
   * This means that bridge clients will use IPv4 DirPorts by default.
   */
  node_get_prim_dirport(node, &ipv4_addr);
  if (!reachable_addr_use_ipv6(options)) {
    return 0;
  } else if (!tor_addr_port_is_valid_ap(&ipv4_addr, 0)
      || reachable_addr_prefer_ipv6_dirport(get_options())) {
    return node_has_ipv6_dirport(node);
  }
  return 0;
}

/** Copy the primary (IPv4) Dir port (IP address and TCP port) for <b>node</b>
 * into *<b>ap_out</b>. */
void
node_get_prim_dirport(const node_t *node, tor_addr_port_t *ap_out)
{
  node_assert_ok(node);
  tor_assert(ap_out);

  /* Clear the address, as a safety precaution if calling functions ignore the
   * return value */
  tor_addr_make_null(&ap_out->addr, AF_INET);
  ap_out->port = 0;

  /* Check ri first, because rewrite_node_address_for_bridge() updates
   * node->ri with the configured bridge address. */

  RETURN_IPV4_AP(node->ri, ipv4_dirport, ap_out);
  RETURN_IPV4_AP(node->rs, ipv4_dirport, ap_out);
  /* Microdescriptors only have an IPv6 address */
}

#undef RETURN_IPV4_AP

/** Copy the preferred Dir port (IP address and TCP port) for
 * <b>node</b> into *<b>ap_out</b>.  */
void
node_get_pref_dirport(const node_t *node, tor_addr_port_t *ap_out)
{
  tor_assert(ap_out);

  if (node_ipv6_dir_preferred(node)) {
    node_get_pref_ipv6_dirport(node, ap_out);
  } else {
    /* the primary DirPort is always on IPv4 */
    node_get_prim_dirport(node, ap_out);
  }
}

/** Copy the preferred IPv6 Dir port (IP address and TCP port) for
 * <b>node</b> into *<b>ap_out</b>. */
void
node_get_pref_ipv6_dirport(const node_t *node, tor_addr_port_t *ap_out)
{
  node_assert_ok(node);
  tor_assert(ap_out);

  /* Check ri first, because rewrite_node_address_for_bridge() updates
   * node->ri with the configured bridge address.
   * Prefer rs over md for consistency with the fascist_firewall_* functions.
   * Check if the address or port are valid, and try another alternative
   * if they are not. */

  /* Assume IPv4 and IPv6 dirports are the same */
  if (node->ri && tor_addr_port_is_valid(&node->ri->ipv6_addr,
                                         node->ri->ipv4_dirport, 0)) {
    tor_addr_copy(&ap_out->addr, &node->ri->ipv6_addr);
    ap_out->port = node->ri->ipv4_dirport;
  } else if (node->rs && tor_addr_port_is_valid(&node->rs->ipv6_addr,
                                                node->rs->ipv4_dirport, 0)) {
    tor_addr_copy(&ap_out->addr, &node->rs->ipv6_addr);
    ap_out->port = node->rs->ipv4_dirport;
  } else {
    tor_addr_make_null(&ap_out->addr, AF_INET6);
    ap_out->port = 0;
  }
}

/** Return true iff <b>md</b> has a curve25519 onion key.
 * Use node_has_curve25519_onion_key() instead of calling this directly. */
static int
microdesc_has_curve25519_onion_key(const microdesc_t *md)
{
  if (!md) {
    return 0;
  }

  if (!md->onion_curve25519_pkey) {
    return 0;
  }

  if (fast_mem_is_zero((const char*)md->onion_curve25519_pkey->public_key,
                      CURVE25519_PUBKEY_LEN)) {
    return 0;
  }

  return 1;
}

/** Return true iff <b>node</b> has a curve25519 onion key. */
int
node_has_curve25519_onion_key(const node_t *node)
{
  return node_get_curve25519_onion_key(node) != NULL;
}

/** Return the curve25519 key of <b>node</b>, or NULL if none. */
const curve25519_public_key_t *
node_get_curve25519_onion_key(const node_t *node)
{
  if (!node)
    return NULL;
  if (routerinfo_has_curve25519_onion_key(node->ri))
    return node->ri->onion_curve25519_pkey;
  else if (microdesc_has_curve25519_onion_key(node->md))
    return node->md->onion_curve25519_pkey;
  else
    return NULL;
}

/* Return a newly allocacted RSA onion public key taken from the given node.
 *
 * Return NULL if node is NULL or no RSA onion public key can be found. It is
 * the caller responsibility to free the returned object. */
crypto_pk_t *
node_get_rsa_onion_key(const node_t *node)
{
  crypto_pk_t *pk = NULL;
  const char *onion_pkey;
  size_t onion_pkey_len;

  if (!node) {
    goto end;
  }

  if (node->ri) {
    onion_pkey = node->ri->onion_pkey;
    onion_pkey_len = node->ri->onion_pkey_len;
  } else if (node->rs && node->md) {
    onion_pkey = node->md->onion_pkey;
    onion_pkey_len = node->md->onion_pkey_len;
  } else {
    /* No descriptor or microdescriptor. */
    goto end;
  }
  pk = router_get_rsa_onion_pkey(onion_pkey, onion_pkey_len);

 end:
  return pk;
}

/** Refresh the country code of <b>ri</b>.  This function MUST be called on
 * each router when the GeoIP database is reloaded, and on all new routers. */
void
node_set_country(node_t *node)
{
  const tor_addr_t *ipv4_addr = NULL;

  /* XXXXipv6 */
  if (node->rs)
    ipv4_addr = &node->rs->ipv4_addr;
  else if (node->ri)
    ipv4_addr = &node->ri->ipv4_addr;

  /* IPv4 is mandatory for a relay so this should not happen unless we are
   * attempting to set the country code on a node without a descriptor. */
  if (BUG(!ipv4_addr)) {
    node->country = -1;
    return;
  }
  node->country = geoip_get_country_by_addr(ipv4_addr);
}

/** Set the country code of all routers in the routerlist. */
void
nodelist_refresh_countries(void)
{
  const smartlist_t *nodes = nodelist_get_list();
  SMARTLIST_FOREACH(nodes, node_t *, node,
                    node_set_country(node));
}

/** Return true iff router1 and router2 have similar enough network addresses
 * that we should treat them as being in the same family */
int
router_addrs_in_same_network(const tor_addr_t *a1,
                             const tor_addr_t *a2)
{
  if (tor_addr_is_null(a1) || tor_addr_is_null(a2))
    return 0;

  switch (tor_addr_family(a1)) {
    case AF_INET:
      return 0 == tor_addr_compare_masked(a1, a2, 16, CMP_SEMANTIC);
    case AF_INET6:
      return 0 == tor_addr_compare_masked(a1, a2, 32, CMP_SEMANTIC);
    default:
      /* If not IPv4 or IPv6, return 0. */
      return 0;
  }
}

/** Return true if <b>node</b>'s nickname matches <b>nickname</b>
 * (case-insensitive), or if <b>node's</b> identity key digest
 * matches a hexadecimal value stored in <b>nickname</b>.  Return
 * false otherwise. */
STATIC int
node_nickname_matches(const node_t *node, const char *nickname)
{
  const char *n = node_get_nickname(node);
  if (n && nickname[0]!='$' && !strcasecmp(n, nickname))
    return 1;
  return hex_digest_nickname_matches(nickname,
                                     node->identity,
                                     n);
}

/** Return true iff <b>node</b> is named by some nickname in <b>lst</b>. */
STATIC int
node_in_nickname_smartlist(const smartlist_t *lst, const node_t *node)
{
  if (!lst) return 0;
  SMARTLIST_FOREACH(lst, const char *, name, {
    if (node_nickname_matches(node, name))
      return 1;
  });
  return 0;
}

/** Return true iff n1's declared family contains n2. */
STATIC int
node_family_contains(const node_t *n1, const node_t *n2)
{
  if (n1->ri && n1->ri->declared_family) {
    return node_in_nickname_smartlist(n1->ri->declared_family, n2);
  } else if (n1->md) {
    return nodefamily_contains_node(n1->md->family, n2);
  } else {
    return 0;
  }
}

/**
 * Return true iff <b>node</b> has declared a nonempty family.
 **/
STATIC bool
node_has_declared_family(const node_t *node)
{
  if (node->ri && node->ri->declared_family &&
      smartlist_len(node->ri->declared_family)) {
    return true;
  }

  if (node->md && node->md->family) {
    return true;
  }

  return false;
}

/**
 * Add to <b>out</b> every node_t that is listed by <b>node</b> as being in
 * its family.  (Note that these nodes are not in node's family unless they
 * also agree that node is in their family.)
 **/
STATIC void
node_lookup_declared_family(smartlist_t *out, const node_t *node)
{
  if (node->ri && node->ri->declared_family &&
      smartlist_len(node->ri->declared_family)) {
    SMARTLIST_FOREACH_BEGIN(node->ri->declared_family, const char *, name) {
      const node_t *n2 = node_get_by_nickname(name, NNF_NO_WARN_UNNAMED);
      if (n2) {
        smartlist_add(out, (node_t *)n2);
      }
    } SMARTLIST_FOREACH_END(name);
    return;
  }

  if (node->md && node->md->family) {
    nodefamily_add_nodes_to_smartlist(node->md->family, out);
  }
}

/** Return true iff r1 and r2 are in the same family, but not the same
 * router. */
int
nodes_in_same_family(const node_t *node1, const node_t *node2)
{
  const or_options_t *options = get_options();

  /* Are they in the same family because of their addresses? */
  if (options->EnforceDistinctSubnets) {
    tor_addr_t a1, a2;
    node_get_addr(node1, &a1);
    node_get_addr(node2, &a2);

    tor_addr_port_t ap6_1, ap6_2;
    node_get_pref_ipv6_orport(node1, &ap6_1);
    node_get_pref_ipv6_orport(node2, &ap6_2);

    if (router_addrs_in_same_network(&a1, &a2) ||
        router_addrs_in_same_network(&ap6_1.addr, &ap6_2.addr))
      return 1;
  }

  /* Are they in the same family because the agree they are? */
  if (node_family_contains(node1, node2) &&
      node_family_contains(node2, node1)) {
    return 1;
  }

  /* Are they in the same family because the user says they are? */
  if (options->NodeFamilySets) {
    SMARTLIST_FOREACH(options->NodeFamilySets, const routerset_t *, rs, {
        if (routerset_contains_node(rs, node1) &&
            routerset_contains_node(rs, node2))
          return 1;
      });
  }

  return 0;
}

/**
 * Add all the family of <b>node</b>, including <b>node</b> itself, to
 * the smartlist <b>sl</b>.
 *
 * This is used to make sure we don't pick siblings in a single path, or
 * pick more than one relay from a family for our entry guard list.
 * Note that a node may be added to <b>sl</b> more than once if it is
 * part of <b>node</b>'s family for more than one reason.
 */
void
nodelist_add_node_and_family(smartlist_t *sl, const node_t *node)
{
  const smartlist_t *all_nodes = nodelist_get_list();
  const or_options_t *options = get_options();

  tor_assert(node);

  /* Let's make sure that we have the node itself, if it's a real node. */
  {
    const node_t *real_node = node_get_by_id(node->identity);
    if (real_node)
      smartlist_add(sl, (node_t*)real_node);
  }

  /* First, add any nodes with similar network addresses. */
  if (options->EnforceDistinctSubnets) {
    tor_addr_t node_addr;
    tor_addr_port_t node_ap6;
    node_get_addr(node, &node_addr);
    node_get_pref_ipv6_orport(node, &node_ap6);

    SMARTLIST_FOREACH_BEGIN(all_nodes, const node_t *, node2) {
      tor_addr_t a;
      tor_addr_port_t ap6;
      node_get_addr(node2, &a);
      node_get_pref_ipv6_orport(node2, &ap6);
      if (router_addrs_in_same_network(&a, &node_addr) ||
          router_addrs_in_same_network(&ap6.addr, &node_ap6.addr))
        smartlist_add(sl, (void*)node2);
    } SMARTLIST_FOREACH_END(node2);
  }

  /* Now, add all nodes in the declared family of this node, if they
   * also declare this node to be in their family. */
  if (node_has_declared_family(node)) {
    smartlist_t *declared_family = smartlist_new();
    node_lookup_declared_family(declared_family, node);

    /* Add every r such that router declares familyness with node, and node
     * declares familyhood with router. */
    SMARTLIST_FOREACH_BEGIN(declared_family, const node_t *, node2) {
      if (node_family_contains(node2, node)) {
        smartlist_add(sl, (void*)node2);
      }
    } SMARTLIST_FOREACH_END(node2);
    smartlist_free(declared_family);
  }

  /* If the user declared any families locally, honor those too. */
  if (options->NodeFamilySets) {
    SMARTLIST_FOREACH(options->NodeFamilySets, const routerset_t *, rs, {
      if (routerset_contains_node(rs, node)) {
        routerset_get_all_nodes(sl, rs, NULL, 0);
      }
    });
  }
}

/** Find a router that's up, that has this IP address, and
 * that allows exit to this address:port, or return NULL if there
 * isn't a good one.
 * Don't exit enclave to excluded relays -- it wouldn't actually
 * hurt anything, but this way there are fewer confused users.
 */
const node_t *
router_find_exact_exit_enclave(const char *address, uint16_t port)
{/*XXXX MOVE*/
  struct in_addr in;
  tor_addr_t ipv4_addr;
  const or_options_t *options = get_options();

  if (!tor_inet_aton(address, &in))
    return NULL; /* it's not an IP already */
  tor_addr_from_in(&ipv4_addr, &in);

  SMARTLIST_FOREACH(nodelist_get_list(), const node_t *, node, {
    if (tor_addr_eq(node_get_prim_addr_ipv4(node), &ipv4_addr) &&
        node->is_running &&
        compare_tor_addr_to_node_policy(&ipv4_addr, port, node) ==
          ADDR_POLICY_ACCEPTED &&
        !routerset_contains_node(options->ExcludeExitNodesUnion_, node))
      return node;
  });
  return NULL;
}

/** Return 1 if <b>router</b> is not suitable for these parameters, else 0.
 * If <b>need_uptime</b> is non-zero, we require a minimum uptime.
 * If <b>need_capacity</b> is non-zero, we require a minimum advertised
 * bandwidth.
 * If <b>need_guard</b>, we require that the router is a possible entry guard.
 */
int
node_is_unreliable(const node_t *node, int need_uptime,
                   int need_capacity, int need_guard)
{
  if (need_uptime && !node->is_stable)
    return 1;
  if (need_capacity && !node->is_fast)
    return 1;
  if (need_guard && !node->is_possible_guard)
    return 1;
  return 0;
}

/** Return 1 if all running sufficiently-stable routers we can use will reject
 * addr:port. Return 0 if any might accept it. */
int
router_exit_policy_all_nodes_reject(const tor_addr_t *addr, uint16_t port,
                                    int need_uptime)
{
  addr_policy_result_t r;

  SMARTLIST_FOREACH_BEGIN(nodelist_get_list(), const node_t *, node) {
    if (node->is_running &&
        !node_is_unreliable(node, need_uptime, 0, 0)) {

      r = compare_tor_addr_to_node_policy(addr, port, node);

      if (r != ADDR_POLICY_REJECTED && r != ADDR_POLICY_PROBABLY_REJECTED)
        return 0; /* this one could be ok. good enough. */
    }
  } SMARTLIST_FOREACH_END(node);
  return 1; /* all will reject. */
}

/** Mark the router with ID <b>digest</b> as running or non-running
 * in our routerlist. */
void
router_set_status(const char *digest, int up)
{
  node_t *node;
  tor_assert(digest);

  SMARTLIST_FOREACH(router_get_fallback_dir_servers(),
                    dir_server_t *, d,
                    if (tor_memeq(d->digest, digest, DIGEST_LEN))
                      d->is_running = up);

  SMARTLIST_FOREACH(router_get_trusted_dir_servers(),
                    dir_server_t *, d,
                    if (tor_memeq(d->digest, digest, DIGEST_LEN))
                      d->is_running = up);

  node = node_get_mutable_by_id(digest);
  if (node) {
#if 0
    log_debug(LD_DIR,"Marking router %s as %s.",
              node_describe(node), up ? "up" : "down");
#endif
    if (!up && node_is_me(node) && !net_is_disabled())
      log_warn(LD_NET, "We just marked ourself as down. Are your external "
               "addresses reachable?");

    if (bool_neq(node->is_running, up))
      router_dir_info_changed();

    node->is_running = up;
  }
}

/** True iff, the last time we checked whether we had enough directory info
 * to build circuits, the answer was "yes". If there are no exits in the
 * consensus, we act as if we have 100% of the exit directory info. */
static int have_min_dir_info = 0;

/** Does the consensus contain nodes that can exit? */
static consensus_path_type_t have_consensus_path = CONSENSUS_PATH_UNKNOWN;

/** True iff enough has changed since the last time we checked whether we had
 * enough directory info to build circuits that our old answer can no longer
 * be trusted. */
static int need_to_update_have_min_dir_info = 1;
/** String describing what we're missing before we have enough directory
 * info. */
static char dir_info_status[512] = "";

/** Return true iff we have enough consensus information to
 * start building circuits.  Right now, this means "a consensus that's
 * less than a day old, and at least 60% of router descriptors (configurable),
 * weighted by bandwidth. Treat the exit fraction as 100% if there are
 * no exits in the consensus."
 * To obtain the final weighted bandwidth, we multiply the
 * weighted bandwidth fraction for each position (guard, middle, exit). */
MOCK_IMPL(int,
router_have_minimum_dir_info,(void))
{
  static int logged_delay=0;
  const char *delay_fetches_msg = NULL;
  if (should_delay_dir_fetches(get_options(), &delay_fetches_msg)) {
    if (!logged_delay)
      log_notice(LD_DIR, "Delaying directory fetches: %s", delay_fetches_msg);
    logged_delay=1;
    strlcpy(dir_info_status, delay_fetches_msg,  sizeof(dir_info_status));
    return 0;
  }
  logged_delay = 0; /* reset it if we get this far */

  if (PREDICT_UNLIKELY(need_to_update_have_min_dir_info)) {
    update_router_have_minimum_dir_info();
  }

  return have_min_dir_info;
}

/** Set to CONSENSUS_PATH_EXIT if there is at least one exit node
 * in the consensus. We update this flag in compute_frac_paths_available if
 * there is at least one relay that has an Exit flag in the consensus.
 * Used to avoid building exit circuits when they will almost certainly fail.
 * Set to CONSENSUS_PATH_INTERNAL if there are no exits in the consensus.
 * (This situation typically occurs during bootstrap of a test network.)
 * Set to CONSENSUS_PATH_UNKNOWN if we have never checked, or have
 * reason to believe our last known value was invalid or has expired.
 * If we're in a network with TestingDirAuthVoteExit set,
 * this can cause router_have_consensus_path() to be set to
 * CONSENSUS_PATH_EXIT, even if there are no nodes with accept exit policies.
 */
MOCK_IMPL(consensus_path_type_t,
router_have_consensus_path, (void))
{
  return have_consensus_path;
}

/** Called when our internal view of the directory has changed.  This can be
 * when the authorities change, networkstatuses change, the list of routerdescs
 * changes, or number of running routers changes.
 */
void
router_dir_info_changed(void)
{
  need_to_update_have_min_dir_info = 1;
  rend_hsdir_routers_changed();
  hs_service_dir_info_changed();
  hs_client_dir_info_changed();
}

/** Return a string describing what we're missing before we have enough
 * directory info. */
const char *
get_dir_info_status_string(void)
{
  return dir_info_status;
}

/** Iterate over the servers listed in <b>consensus</b>, and count how many of
 * them seem like ones we'd use (store this in *<b>num_usable</b>), and how
 * many of <em>those</em> we have descriptors for (store this in
 * *<b>num_present</b>).
 *
 * If <b>in_set</b> is non-NULL, only consider those routers in <b>in_set</b>.
 * If <b>exit_only</b> & USABLE_DESCRIPTOR_EXIT_POLICY, only consider nodes
 * present if they have an exit policy that accepts at least one port.
 * If <b>exit_only</b> & USABLE_DESCRIPTOR_EXIT_FLAG, only consider nodes
 * usable if they have the exit flag in the consensus.
 *
 * If *<b>descs_out</b> is present, add a node_t for each usable descriptor
 * to it.
 */
static void
count_usable_descriptors(int *num_present, int *num_usable,
                         smartlist_t *descs_out,
                         const networkstatus_t *consensus,
                         time_t now,
                         routerset_t *in_set,
                         usable_descriptor_t exit_only)
{
  const int md = (consensus->flavor == FLAV_MICRODESC);
  *num_present = 0, *num_usable = 0;

  SMARTLIST_FOREACH_BEGIN(consensus->routerstatus_list, routerstatus_t *, rs)
    {
       const node_t *node = node_get_by_id(rs->identity_digest);
       if (!node)
         continue; /* This would be a bug: every entry in the consensus is
                    * supposed to have a node. */
       if ((exit_only & USABLE_DESCRIPTOR_EXIT_FLAG) && ! rs->is_exit)
         continue;
       if (in_set && ! routerset_contains_routerstatus(in_set, rs, -1))
         continue;
       if (client_would_use_router(rs, now)) {
         const char * const digest = rs->descriptor_digest;
         int present;
         ++*num_usable; /* the consensus says we want it. */
         if (md)
           present = NULL != microdesc_cache_lookup_by_digest256(NULL, digest);
         else
           present = NULL != router_get_by_descriptor_digest(digest);
         if (present) {
           /* Do the policy check last, because it requires a descriptor,
            * and is potentially expensive */
           if ((exit_only & USABLE_DESCRIPTOR_EXIT_POLICY) &&
               node_exit_policy_rejects_all(node)) {
               continue;
           }
           /* we have the descriptor listed in the consensus, and it
            * satisfies our exit constraints (if any) */
           ++*num_present;
         }
         if (descs_out)
           smartlist_add(descs_out, (node_t*)node);
       }
     }
  SMARTLIST_FOREACH_END(rs);

  log_debug(LD_DIR, "%d usable, %d present (%s%s%s%s%s).",
            *num_usable, *num_present,
            md ? "microdesc" : "desc",
            (exit_only & USABLE_DESCRIPTOR_EXIT_POLICY_AND_FLAG) ?
              " exit"     : "s",
            (exit_only & USABLE_DESCRIPTOR_EXIT_POLICY) ?
              " policies" : "" ,
            (exit_only == USABLE_DESCRIPTOR_EXIT_POLICY_AND_FLAG) ?
              " and" : "" ,
            (exit_only & USABLE_DESCRIPTOR_EXIT_FLAG) ?
              " flags"    : "" );
}

/** Return an estimate of which fraction of usable paths through the Tor
 * network we have available for use.  Count how many routers seem like ones
 * we'd use (store this in *<b>num_usable_out</b>), and how many of
 * <em>those</em> we have descriptors for (store this in
 * *<b>num_present_out</b>.)
 *
 * If **<b>status_out</b> is present, allocate a new string and print the
 * available percentages of guard, middle, and exit nodes to it, noting
 * whether there are exits in the consensus.
 * If there are no exits in the consensus, we treat the exit fraction as 100%,
 * but set router_have_consensus_path() so that we can only build internal
 * paths. */
static double
compute_frac_paths_available(const networkstatus_t *consensus,
                             const or_options_t *options, time_t now,
                             int *num_present_out, int *num_usable_out,
                             char **status_out)
{
  smartlist_t *guards = smartlist_new();
  smartlist_t *mid    = smartlist_new();
  smartlist_t *exits  = smartlist_new();
  double f_guard, f_mid, f_exit;
  double f_path = 0.0;
  /* Used to determine whether there are any exits in the consensus */
  int np = 0;
  /* Used to determine whether there are any exits with descriptors */
  int nu = 0;
  const int authdir = authdir_mode_v3(options);

  count_usable_descriptors(num_present_out, num_usable_out,
                           mid, consensus, now, options->MiddleNodes,
                           USABLE_DESCRIPTOR_ALL);
  log_debug(LD_NET,
            "%s: %d present, %d usable",
            "mid",
            np,
            nu);

  if (options->EntryNodes) {
    count_usable_descriptors(&np, &nu, guards, consensus, now,
                             options->EntryNodes, USABLE_DESCRIPTOR_ALL);
    log_debug(LD_NET,
              "%s: %d present, %d usable",
              "guard",
              np,
              nu);
  } else {
    SMARTLIST_FOREACH(mid, const node_t *, node, {
      if (authdir) {
        if (node->rs && node->rs->is_possible_guard)
          smartlist_add(guards, (node_t*)node);
      } else {
        if (node->is_possible_guard)
          smartlist_add(guards, (node_t*)node);
      }
    });
    log_debug(LD_NET,
              "%s: %d possible",
              "guard",
              smartlist_len(guards));
  }

  /* All nodes with exit policy and flag */
  count_usable_descriptors(&np, &nu, exits, consensus, now,
                           NULL, USABLE_DESCRIPTOR_EXIT_POLICY_AND_FLAG);
  log_debug(LD_NET,
            "%s: %d present, %d usable",
            "exits",
            np,
            nu);

  /* We need at least 1 exit (flag and policy) in the consensus to consider
   * building exit paths */
  /* Update our understanding of whether the consensus has exits */
  consensus_path_type_t old_have_consensus_path = have_consensus_path;
  have_consensus_path = ((np > 0) ?
                         CONSENSUS_PATH_EXIT :
                         CONSENSUS_PATH_INTERNAL);

  if (old_have_consensus_path != have_consensus_path) {
    if (have_consensus_path == CONSENSUS_PATH_INTERNAL) {
      log_notice(LD_NET,
                 "The current consensus has no exit nodes. "
                 "Tor can only build internal paths, "
                 "such as paths to onion services.");

      /* However, exit nodes can reachability self-test using this consensus,
       * join the network, and appear in a later consensus. This will allow
       * the network to build exit paths, such as paths for world wide web
       * browsing (as distinct from hidden service web browsing). */
    } else if (old_have_consensus_path == CONSENSUS_PATH_INTERNAL) {
      log_notice(LD_NET,
                 "The current consensus contains exit nodes. "
                 "Tor can build exit and internal paths.");
    }
  }

  f_guard = frac_nodes_with_descriptors(guards, WEIGHT_FOR_GUARD, 1);
  f_mid   = frac_nodes_with_descriptors(mid,    WEIGHT_FOR_MID,   0);
  f_exit  = frac_nodes_with_descriptors(exits,  WEIGHT_FOR_EXIT,  0);

  /* If we are using bridges and have at least one bridge with a full
   * descriptor, assume f_guard is 1.0. */
  if (options->UseBridges && num_bridges_usable(0) > 0)
    f_guard = 1.0;

  log_debug(LD_NET,
            "f_guard: %.2f, f_mid: %.2f, f_exit: %.2f",
             f_guard,
             f_mid,
             f_exit);

  smartlist_free(guards);
  smartlist_free(mid);
  smartlist_free(exits);

  if (options->ExitNodes) {
    double f_myexit, f_myexit_unflagged;
    smartlist_t *myexits= smartlist_new();
    smartlist_t *myexits_unflagged = smartlist_new();

    /* All nodes with exit policy and flag in ExitNodes option */
    count_usable_descriptors(&np, &nu, myexits, consensus, now,
                             options->ExitNodes,
                             USABLE_DESCRIPTOR_EXIT_POLICY_AND_FLAG);
    log_debug(LD_NET,
              "%s: %d present, %d usable",
              "myexits",
              np,
              nu);

    /* Now compute the nodes in the ExitNodes option where we know their exit
     * policy permits something. */
    count_usable_descriptors(&np, &nu, myexits_unflagged,
                             consensus, now,
                             options->ExitNodes,
                             USABLE_DESCRIPTOR_EXIT_POLICY);
    log_debug(LD_NET,
              "%s: %d present, %d usable",
              "myexits_unflagged (initial)",
              np,
              nu);

    f_myexit= frac_nodes_with_descriptors(myexits,WEIGHT_FOR_EXIT, 0);
    f_myexit_unflagged=
              frac_nodes_with_descriptors(myexits_unflagged,
                                          WEIGHT_FOR_EXIT, 0);

    log_debug(LD_NET,
              "f_exit: %.2f, f_myexit: %.2f, f_myexit_unflagged: %.2f",
              f_exit,
              f_myexit,
              f_myexit_unflagged);

    /* If our ExitNodes list has eliminated every possible Exit node, and there
     * were some possible Exit nodes, then instead consider nodes that permit
     * exiting to some ports. */
    if (smartlist_len(myexits) == 0 &&
        smartlist_len(myexits_unflagged)) {
      f_myexit = f_myexit_unflagged;
    }

    smartlist_free(myexits);
    smartlist_free(myexits_unflagged);

    /* This is a tricky point here: we don't want to make it easy for a
     * directory to trickle exits to us until it learns which exits we have
     * configured, so require that we have a threshold both of total exits
     * and usable exits. */
    if (f_myexit < f_exit)
      f_exit = f_myexit;
  }

  /* If the consensus has no exits that pass flag, descriptor, and policy
   * checks, we can only build onion service paths, which are G - M - M. */
  if (router_have_consensus_path() != CONSENSUS_PATH_EXIT) {
    /* If the exit bandwidth weight fraction is not zero, we need to wait for
     * descriptors for those exits. (The bandwidth weight fraction does not
     * check for descriptors.)
     * If the exit bandwidth fraction is zero, there are no exits in the
     * consensus at all. So it is safe to replace f_exit with f_mid.
     *
     * f_exit is non-negative, but some compilers complain about float and ==
     */
    if (f_exit <= 0.0) {
      f_exit = f_mid;
    }
  }

  f_path = f_guard * f_mid * f_exit;

  if (status_out)
    tor_asprintf(status_out,
                 "%d%% of guards bw, "
                 "%d%% of midpoint bw, and "
                 "%d%% of %s = "
                 "%d%% of path bw",
                 (int)(f_guard*100),
                 (int)(f_mid*100),
                 (int)(f_exit*100),
                 (router_have_consensus_path() == CONSENSUS_PATH_EXIT ?
                  "exit bw" :
                  "end bw (no exits in consensus, using mid)"),
                 (int)(f_path*100));

  return f_path;
}

/** We just fetched a new set of descriptors. Compute how far through
 * the "loading descriptors" bootstrapping phase we are, so we can inform
 * the controller of our progress. */
int
count_loading_descriptors_progress(void)
{
  int num_present = 0, num_usable=0;
  time_t now = time(NULL);
  const or_options_t *options = get_options();
  const networkstatus_t *consensus =
    networkstatus_get_reasonably_live_consensus(now,usable_consensus_flavor());
  double paths, fraction;

  if (!consensus)
    return 0; /* can't count descriptors if we have no list of them */

  paths = compute_frac_paths_available(consensus, options, now,
                                       &num_present, &num_usable,
                                       NULL);

  fraction = paths / get_frac_paths_needed_for_circs(options,consensus);
  if (fraction > 1.0)
    return 0; /* it's not the number of descriptors holding us back */
  return BOOTSTRAP_STATUS_LOADING_DESCRIPTORS + (int)
    (fraction*(BOOTSTRAP_STATUS_ENOUGH_DIRINFO-1 -
               BOOTSTRAP_STATUS_LOADING_DESCRIPTORS));
}

/** Return the fraction of paths needed before we're willing to build
 * circuits, as configured in <b>options</b>, or in the consensus <b>ns</b>. */
static double
get_frac_paths_needed_for_circs(const or_options_t *options,
                                const networkstatus_t *ns)
{
#define DFLT_PCT_USABLE_NEEDED 60
  if (options->PathsNeededToBuildCircuits >= 0.0) {
    return options->PathsNeededToBuildCircuits;
  } else {
    return networkstatus_get_param(ns, "min_paths_for_circs_pct",
                                   DFLT_PCT_USABLE_NEEDED,
                                   25, 95)/100.0;
  }
}

/** Change the value of have_min_dir_info, setting it true iff we have enough
 * network and router information to build circuits.  Clear the value of
 * need_to_update_have_min_dir_info. */
static void
update_router_have_minimum_dir_info(void)
{
  time_t now = time(NULL);
  int res;
  int num_present=0, num_usable=0;
  const or_options_t *options = get_options();
  const networkstatus_t *consensus =
    networkstatus_get_reasonably_live_consensus(now,usable_consensus_flavor());
  int using_md;

  if (!consensus) {
    if (!networkstatus_get_latest_consensus())
      strlcpy(dir_info_status, "We have no usable consensus.",
              sizeof(dir_info_status));
    else
      strlcpy(dir_info_status, "We have no recent usable consensus.",
              sizeof(dir_info_status));
    res = 0;
    goto done;
  }

  using_md = consensus->flavor == FLAV_MICRODESC;

  /* Check fraction of available paths */
  {
    char *status = NULL;
    double paths = compute_frac_paths_available(consensus, options, now,
                                                &num_present, &num_usable,
                                                &status);

    if (paths < get_frac_paths_needed_for_circs(options,consensus)) {
      tor_snprintf(dir_info_status, sizeof(dir_info_status),
                   "We need more %sdescriptors: we have %d/%d, and "
                   "can only build %d%% of likely paths. (We have %s.)",
                   using_md?"micro":"", num_present, num_usable,
                   (int)(paths*100), status);
      tor_free(status);
      res = 0;
      control_event_boot_dir(BOOTSTRAP_STATUS_REQUESTING_DESCRIPTORS, 0);
      goto done;
    }

    tor_free(status);
    res = 1;
  }

  { /* Check entry guard dirinfo status */
    char *guard_error = entry_guards_get_err_str_if_dir_info_missing(using_md,
                                                             num_present,
                                                             num_usable);
    if (guard_error) {
      strlcpy(dir_info_status, guard_error, sizeof(dir_info_status));
      tor_free(guard_error);
      res = 0;
      goto done;
    }
  }

 done:

  /* If paths have just become available in this update. */
  if (res && !have_min_dir_info) {
    control_event_client_status(LOG_NOTICE, "ENOUGH_DIR_INFO");
    control_event_boot_dir(BOOTSTRAP_STATUS_ENOUGH_DIRINFO, 0);
    log_info(LD_DIR,
             "We now have enough directory information to build circuits.");
  }

  /* If paths have just become unavailable in this update. */
  if (!res && have_min_dir_info) {
    int quiet = dirclient_too_idle_to_fetch_descriptors(options, now);
    tor_log(quiet ? LOG_INFO : LOG_NOTICE, LD_DIR,
        "Our directory information is no longer up-to-date "
        "enough to build circuits: %s", dir_info_status);

    /* a) make us log when we next complete a circuit, so we know when Tor
     * is back up and usable, and b) disable some activities that Tor
     * should only do while circuits are working, like reachability tests
     * and fetching bridge descriptors only over circuits. */
    note_that_we_maybe_cant_complete_circuits();
    have_consensus_path = CONSENSUS_PATH_UNKNOWN;
    control_event_client_status(LOG_NOTICE, "NOT_ENOUGH_DIR_INFO");
  }
  have_min_dir_info = res;
  need_to_update_have_min_dir_info = 0;
}
